|SYNC(2)||Linux Programmer's Manual||SYNC(2)|
NAMEsync, syncfs - commit buffer cache to disk
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTIONsync() causes all buffered modifications to file metadata and data to be written to the underlying file systems.
RETURN VALUEsyncfs() returns 0 on success; on error, it returns -1 and sets errno to indicate the error.
ERRORSsync() is always successful.
- fd is not a valid file descriptor.
VERSIONSsyncfs() first appeared in Linux 2.6.39; library support was added to glibc in version 2.14.
CONFORMING TOsync(): SVr4, 4.3BSD, POSIX.1-2001.
NOTESSince glibc 2.2.2 the Linux prototype for sync() is as listed above, following the various standards. In libc4, libc5, and glibc up to 2.2.1 it was "int sync(void)", and sync() always returned 0.
BUGSAccording to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However, since version 1.3.20 Linux does actually wait. (This still does not guarantee data integrity: modern disks have large caches.)
SEE ALSObdflush(2), fdatasync(2), fsync(2), sync(8), update(8)
COLOPHONThis page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.